I personally can't even get nxj to work, but it does appear you are using the wrong firmware. You're going to have to hold the hard reset button (located inside the back top left pinhole of the NXT), plug it in, and type "nxjflash".

Of course now that you have both pointed this out, it makes complete and utter sense. All I can say is that it was late .... and I was tired

Having said that, I did take another look at the leJOS README.html file and have to say that it isn't entirely obvious from first reading that the NXT firmware *must* be replaced in order to use leJOS.

Maybe you might consider a small note to this effect in the "Using LEJOS NXJ" section?